Ear thermometer and measuring apparatus used with it

ABSTRACT

An object is to realize an ear thermometer that is configured to easily arrange a sensor in a sensor mirror and is suitable for mass production. The ear thermometer has a probe. The probe includes a probe body and a temperature measuring part joined with the probe body. The temperature measuring part includes a flange coupled with the probe body and a front end part extending from the flange, the front end part incorporating a sensor mirror. The sensor mirror includes a cylindrical holder with an internal concave reflection face, a connection shaft extending from the back of the cylindrical holder, a flexible printed circuit board with a circuit conductor of predetermined pattern, stretched in a front space of the cylindrical holder, a temperature measuring first sensor and a correcting second sensor spaced by a predetermined distance from each other in a longitudinal direction of the board and soldered to the circuit conductor on the board, and a protection cover covering a front face of the cylindrical holder. The board is electrically connected, in the temperature measuring part, to the cable passing through the probe body.

TECHNICAL FIELD

The present invention generally relates to a thermometer to measure thebody temperature of a measuring object, and particularly, to an earthermometer to measure a temperature of the eardrum by inserting atemperature sensing part into an ear hole and a measuring apparatus usedwith the ear thermometer.

BACKGROUND TECHNOLOGY

A typical example of a conventional ear thermometer will be explainedwith reference to FIGS. 15 and 16. FIG. 15 is a circuit block diagramillustrating an operation principle of the conventional ear thermometerand FIG. 16 is a vertical section of a temperature sensing part of theconventional ear thermometer. As illustrated in FIG. 15, a probe 10 ofthe typical conventional ear thermometer employs a thermopile 11.Generally, the thermopile produces a potential difference depending on atemperature difference between a cold junction and a hot junction (theSeebeck effect). Using the thermopile as a temperature measuring probeneeds a room temperature (ambient temperature) compensation like athermocouple. For this, the conventional ear thermometer employs athermistor 12.

If the temperature of a measuring object is equal to a cold junctiontemperature of the thermopile 11, an output from the probe 10 is zero(zero point). On the other hand, if the temperature of the measuringobject is higher than the cold junction temperature of the thermopile11, an output from the probe 10 becomes nonlinearly larger.

When using the probe 10 to measure a body temperature, an output fromthe probe 10 is weak. Accordingly, the output from the probe 10 isamplified by a signal amplifier 13 to a signal processing possiblelevel. A linearizer 14 a linearizes a nonlinear output. An output fromthe thermistor 12 is also nonlinear, and therefore, is linearized by alinearizer 14 b.

In a state in which an ambient temperature is stable, the temperature ofthe thermistor 12 and the cold junction temperature of the thermopile 11are equal to each other. The signal formed by linearizing the outputfrom the probe 10 indicates a difference between the temperature of thethermistor 12 and the temperature of the measuring object. Accordingly,the signal formed by linearizing the output from the probe 10 iscorrected by an emissivity corrector 15, the corrected signal and thesignal formed by linearizing the output from the thermistor 12 arecompensated by an adder 16 for a room temperature or a cold junctiontemperature, and the compensated signal is compensated by a temperatureconverter 17 for an ambient temperature, thereby providing thetemperature of the measuring object, which is displayed on a display 18.

The thermopile involves a large variation in sensitivity due toindividual differences, and therefore, provides a different outputvoltage with respect to a given temperature difference. Accordingly, aprobe employing the thermopile must carry out an individual sensitivityadjustment (calibration work). An infrared absorbing film of thethermopile (a part where the infrared absorbing film and hot junctionare integrated, refer to 116 of FIG. 16) absorbs infrared rays from ameasuring object and increases the temperature thereof. A package of thethermopile also radiates infrared rays to the infrared absorbing film.In normal use, the package is considered to have the same temperature asa heat sink (heat absorbing part) of the thermopile. If an externalfactor applies a sudden temperature change, a head of the package andthe heat sink of the thermopile produce a temperature difference totransiently destabilize the output of the probe.

For this, as illustrated in FIG. 16, to make a temperature change beuniformly and gently applied to the probe 10, the thermopile 110 isarranged inside a metal (for example, aluminum) holder 111 having a goodheat conductivity. In addition, there is arranged a cover 114 tosurround the same with an air layer 112 and resin 113 serving as heatinsulating materials. In front of the thermopile 110, there is arrangeda metal pipe 115 to reduce the influence of heat radiation from themeasuring object. The metal pipe 115 is plated with gold to reduce anemissivity and function as a waveguide. As a cold junction temperaturecompensating sensor, a semiconductor, a thermistor, or the like isemployed. The thermistor is low in manufacturing cost and precise, andtherefore, is generally used.

If thermal bonding between the thermopile cold junction and thethermistor is bad, a temperature difference occurs to prevent a correctmeasurement. The thermistor (not illustrated) and thermopile 110 arearranged in the same package, to improve thermal bonding between theheat sink of the thermopile cold junction and the thermistor. Eventhermistors based on the same standard have different B-constants (theB-constant representing the magnitude of a resistance change obtainedfrom temperatures at optional two points on a resistance-temperaturecharacteristic curve), and therefore, it is difficult for the thermistorto keep accuracy for a wide range of ambient temperatures. For example,for a thermistor of an electronic thermometer used to measure thetemperature of a human body in the range of 34 to 43° C., the thermistoris required to keep an accuracy only for the range of 8° C. If thethermopile must cover an ambient temperature range of 5 to 40° C., thethermistor must be accurate for the range of 35° C. (40−5=35).

According to the structure of the probe 10 illustrated in FIG. 16, anincreasing ambient temperature produces a temperature difference betweenthe thermopile 110 and a front end part of the probe 10, so that thetemperature measuring part becomes to have a higher temperature than thethermopile 110, to cause a positive-direction error. A decreasingambient temperature produces a temperature difference between thethermopile 110 and a front end part of the sensor, so that thetemperature measuring part becomes to have a lower temperature than thethermopile 110, to cause a negative-direction error. To reduce theerror, the thermopile 110 is surrounded with the cover 114 to reduce theinfluence of a temperature change. Enlarging the metal holder 111 islimited by the measuring object. To cope with the error caused by anambient temperature change, a rate of change per unit time of thethermistor in the thermopile package is calculated to correct a probeoutput and reduce the error.

In connection with this, the applicant of the present invention hasproposed in a preceding patent application (refer to Patent Document 1)an ear thermometer that eliminates the influence of an ambienttemperature change of a short time and causes no error due to theambient temperature change.

The ear thermometer according to Patent Document 1 has a probe thatincludes a first heat insulating member made of resin, a second highheat insulating member made of resin connected to a front end part ofthe first heat insulating member, a protection cover to cover the firstheat insulating member and second high heat insulating member, athermistor lead thin line embedded in the first heat insulating memberand second high heat insulating member, and an ultrafast responsethermistor arranged substantially at the center of a front return partof the thermistor lead thin line.

According to the invention of Patent Document 1, a temperature range inwhich the thermistor must keep accuracy is only a body temperature rangeof a measuring object. Unlike the conventional ear thermometer employingthe thermopile, the thermistor is not required to keep a measuringaccuracy for an entire measuring ambient temperature range. As a result,the probe according to the invention of the patent application is notinfluenced by a change in an ambient temperature (a temperature changeof a short time).

The ear thermometer according to Patent Document 1, however, hasproblems of hardly being miniaturized, consuming large power, involvinga complicated circuit, and partly needing expensive parts to increase atotal cost.

The ear thermometer according to Patent Document 1 is appropriate foronce measuring a body temperature in a short period of time, but it isinappropriate for continuously measuring body temperatures for a longperiod of time. Under a special using condition, for example, whenmeasuring the body temperature of a patient during his/her surgery, asufficient time is available in a preparatory stage before the surgery.Namely, if a warm-up time of certain extent (about 10 minutes) isallowed, if a large relative temperature and a quick temperature changeare ignorable (if sensing a temperature change of 1° C. for 10 minutesat the maximum is sufficient), if continuous measurement is needed, andif ambient temperature is relatively stable, the ear thermometeraccording to Patent Document 1 is expensive and is inappropriate.

To obtain an ear thermometer that is capable of continuously measuringthe temperature of a measuring object for a long period of time and isinexpensive and disposable, the applicant of the present invention hasproposed in the succeeding patent application (refer to Patent Document2) an ear thermometer having a measuring apparatus and a probe that isconnected to the measuring apparatus and includes a probe body and atemperature measuring part joined with the probe body. The probe body issubstantially formed in an L-shaped cylinder, a first end thereof isconnected through a cable to the measuring apparatus, and a second endthereof is connected to the temperature measuring part. The temperaturemeasuring part includes a flange joined with the probe body and a frontend part extending from the flange. Inside the front end part, a sensormirror is fitted. The sensor mirror includes a cylindrical holder withan internal concave reflection face, a joint shaft extending from theback of the cylindrical holder, a temperature measuring first sensor anda correcting second sensor supported with lead wires in a front space ofthe cylindrical holder, and a protection cover covering a front face ofthe cylindrical holder. The lead wires supporting the first and secondsensors are passed through the temperature measuring part and probe bodyand are electrically connected to the cable.

In the ear thermometer according to Patent Document 2, a thermistor usedfor the probe must secure an accuracy only for a temperature range inwhich the body temperature of a measuring object varies. Unlike theconventional ear thermometer using a thermopile, the thermistor is notrequired to secure a measurement accuracy for a whole range ofmeasurement ambient temperatures. Under a relatively stable ambienttemperature, it is possible to achieve continuous measurement for a longperiod of time. With a simplified temperature measuring circuit,simplified temperature calibration, miniaturized probe, and simplifiedassembling work for mass production, this ear thermometer is compact andinexpensive. Accordingly, the ear thermometer according to PatentDocument 2 is disposable, is stably and surely attachable to the ear ofa measuring object, and is optimum for, in particular, measuring thebody temperature of a patient during his/her surgery.

The ear thermometer according to Patent Document 2, however, isconfigured to support the first and second sensors with the lead wiresin the sensor mirror, and therefore, the work to solder the sensors andlead wires together and the work to arrange the sensors in the sensormirror need a high skill and a long time. Accordingly, this earthermometer is unsuitable for mass production.

Conventional ear thermometers have the problem that their measuringapparatuses are large in scale, and therefore, it is required to reducethe sizes thereof.

-   Patent Document 1: Japanese Unexamined Patent Application    Publication No. 2006-250883-   Patent Document 2: Japanese Unexamined Patent Application    Publication No. 2007-111363

DISCLOSURE OF INVENTION

An object of the present invention is to provide an ear thermometer thatis based on the ear thermometer of Patent Document 2 and has sensorsthat are configured to be easily installed in a sensor mirror, so thatthe ear thermometer is easily mass-producible.

Another object of the present invention is to provide a measuringapparatus incorporating a microcontroller, to further miniaturize aconventional compact ear thermometer.

An ear thermometer according to an aspect of the present invention is anear thermometer provided with a probe connected to a measuringapparatus. The probe includes a probe body and a temperature measuringpart joined with the probe body. The probe body is substantially formedin an L-shaped cylinder, a first end thereof being connected through acable to the measuring apparatus, a second end thereof being joined withthe temperature measuring part. The temperature measuring part includesa flange coupled with the probe body and a front end part extending fromthe flange, the front end part incorporating a sensor mirror. The sensormirror includes a cylindrical holder with an internal concave reflectionface, a connection shaft extending from the back of the cylindricalholder, a flexible printed circuit board with a circuit conductor ofpredetermined pattern, stretched in a front space of the cylindricalholder, a temperature measuring first sensor and a correcting secondsensor spaced by a predetermined distance from each other in alongitudinal direction of the board and soldered to the circuitconductor on the board, and a protection cover covering a front face ofthe cylindrical holder. The flexible printed circuit board iselectrically connected, in the temperature measuring part, to a firstend of the cable passing through the probe body.

According to the ear thermometer of the above-mentioned aspect, it ispossible that a first projection and a second projection are formedsubstantially at opposing locations in a middle part of an outercircumferential face of the sensor mirror, and a first positioning holeand a second positioning hole are formed on a first end side of theflexible printed circuit board at locations corresponding to the firstand second projections.

According to the ear thermometer of the above-mentioned aspect, it ispossible that the first and second projections are engaged with thefirst and second positioning holes, to guide a second end side of theflexible printed circuit board along the outer circumferential face ofthe sensor mirror in the longitudinal direction and electricallyconnect, in the temperature measuring part, the second end side of theboard to the first end of the cable passed through the probe body.

According to the ear thermometer of the above-mentioned aspect, it ispossible that an infrared transmission hole is formed in a middle partof the flexible printed circuit board stretched in the front space ofthe cylindrical holder and the first sensor and second sensor arearranged on each side of the infrared transmission hole in thelongitudinal direction of the board.

According to the ear thermometer of the above-mentioned aspect, it ispossible that a heat sink conductor is arranged at a middle part on thefirst end side of the flexible printed circuit board stretched in thefront space of the cylindrical holder.

A measuring apparatus for an ear thermometer according to another aspectof the present invention includes a common voltage line, a built-inbattery serving as a power source, a connector to receive a connector ofa probe, having a common voltage terminal connected to the commonvoltage line, a flash-type microcontroller to control a temperaturesensor of the probe, receive a resistance value output signalcorresponding to a measured temperature from the temperature sensor,convert the signal into a digital temperature value, and output thedigital temperature value, the microcontroller having a test port, aprogram write port, and a common voltage port connected to the commonvoltage line, establishing a flash mode when a HIGH voltage higher thana first predetermined voltage is applied to the test port, to enable aprogram to be written through the write port, and establishing a runmode when a LOW voltage lower than the first predetermined voltage isapplied to the test port, a voltage regulator having an input sideconnected to the common voltage line, to provide a constant referencevoltage, and a mode switching circuit connected to the common voltageline, to apply the HIGH voltage to the test port of the microcontrollerwhen a common voltage is higher than a second predetermined voltage,apply the LOW voltage to the test port of the microcontroller when thecommon voltage is lower than the second predetermined voltage, andbypass a leakage current passing from the common voltage line to themode switching circuit toward an output of the voltage regulator so asto combine them together. The connector has the common voltage terminal,a battery power source terminal connected to the built-in battery, aprogram write terminal connected to the write port of themicrocontroller, and a sensor connection terminal to receive theresistance value output signal corresponding to a measured temperaturefrom the temperature sensor of the probe.

According to the measuring apparatus for an ear thermometer of theabove-mentioned aspect, it is possible that the mode switching circuitconsists of a pnp-type transistor having an emitter connected to thecommon voltage line, a collector connected to the test port, and a baseconnected through a bias resistor to the common voltage line, a firstresistor interposed between the collector and the ground, to set avoltage of the collector as the HIGH voltage when the transistor is in aconductive state, and a second resistor interposed between the base ofthe transistor and the output of the regulator.

According to the measuring apparatus for an ear thermometer of theabove-mentioned aspect, it is possible that the mode switching circuitis constituted by connecting two resistors in series between the commonvoltage line and the ground, connecting a plus input terminal of anoperational amplifier operating as a comparator to a connection midpointof the two resistors, connecting a minus terminal of the operationalamplifier through another resistor to the output line of the regulator,and connecting an output terminal of the operational amplifier to thetest port of the microcontroller, so that, when a voltage applied to theplus terminal of the operational amplifier is higher than anintermediate voltage between a battery voltage applied to the commonvoltage line and a program write voltage, the operational amplifier isput in a conductive state to output the common voltage of the commonvoltage line as the HIGH voltage to the test port, and when it is lowerthan the intermediate voltage, the operational amplifier is invertedinto a nonconductive state.

According to the measuring apparatus for an ear thermometer of theabove-mentioned aspect, it is possible that the mode switching circuitis constituted by arranging a CMOS inverter between the common voltageline and the ground, connecting a switching terminal of the CMOSinverter and the output of the regulator to each other through aresistor, and connecting an output of the CMOS inverter to the testport, so that, when a voltage applied to the switching terminal of theCMOS inverter is higher than an intermediate voltage between a batteryvoltage applied to the common voltage line and a program write voltage,the common voltage of the common voltage line is outputted as the HIGHvoltage to the test port, and when it is lower than the intermediatevoltage, an output voltage from the regulator stepped down through theresistor is outputted as the LOW voltage to the test port.

According to the measuring apparatus for an ear thermometer of theabove-mentioned aspect, it is possible that the connector is configuredso that, when connected to a probe connector, the battery power sourceterminal and common voltage terminal are connected to each other throughshort-circuited two terminals of the probe connector, and when connectedto a program write unit connector, the common voltage terminal isconnected to a voltage terminal of the second predetermined voltage ofthe program write unit connector.

According to the ear thermometer of the present invention, the sensor(thermistor) used for the probe is required to secure an accuracy onlyfor a temperature range in which the body temperature of a measuringobject varies. Unlike the conventional ear thermometer using athermopile, the thermistor is not required to keep an accuracy for anentire measuring ambient temperature range. When an ambient temperatureis relatively stable, it can carry out a continuous measurement for along period of time. The sensor is soldered to the circuit conductor ofthe flexible printed circuit board, to simplify assembling work. This isadvantageous for mass production. With the simplified temperaturemeasuring circuit, simplified temperature calibration, and compactprobe, the ear thermometer is small and inexpensive. The ear thermometeraccording to the present invention, therefore, is disposable and isstably and surely attachable to the ear of a measuring object.Accordingly, it is optimum for measuring, in particular, the bodytemperature of a measuring object during an operation.

According to the measuring apparatus for an ear thermometer of thepresent invention, the program write mode (flash mode) of themicrocontroller incorporated in the measuring apparatus and the run modeto execute a written program are switched from one to another withoutusing a mode switch of the microcontroller. Instead, the flash mode isestablished if a voltage applied to the test port of the microcontrolleris HIGH, and if it is LOW, the run mode is established. Accordingly,only by preparing a program write unit that applies the HIGH voltage tothe test port of the microcontroller and by connecting the program writeunit to the connector of the measuring apparatus, the microcontroller isautomatically shifted to the flash mode. As a result, the measuringapparatus for an ear thermometer according to the present inventionneeds no mode switch for the microcontroller, thereby simplifying acircuit configuration and miniaturizing the apparatus.

According to the measuring apparatus for an ear thermometer of thepresent invention, the mode switching circuit may employ the transistor.In this case, the first resistor is arranged between the common voltageline and the collector of the transistor, to set a voltage of thecollector to the HIGH voltage when the transistor is in a conductivestate. The second resistor is interposed between the base of thetransistor and the output of the regulator, so that, when the transistoris OFF, a leakage current passes from the common voltage line throughthe first and second resistors to the output side of the regulator andcombines with an output current of the regulator. This reduces an inputcurrent of the regulator itself by the leakage current in the run mode.As a result, the insertion of the mode switching circuit causes nosubstantial change in power consumption. This results in suppressing thepower consumption of the apparatus and extending the power of thebattery.

According to the measuring apparatus for an ear thermometer of thepresent invention, the mode switching circuit may employ the operationalamplifier. In this case, the common voltage is set to a high voltage toinvert the operational amplifier into a conductive state, so that thecommon voltage is outputted as the HIGH voltage to the test port of themicrocontroller. When the common voltage is set to a low voltage, i.e.,a battery voltage, the operational amplifier is again inverted into anonconductive state so that the operational amplifier outputs the LOWvoltage to the test port of the microcontroller. During the run mode ofthe microcontroller, which is a normal operating state of themicrocontroller, no battery current is passed to the mode switchingcircuit. As a result, the insertion of the mode switching circuit causesno substantial change in power consumption. This results in suppressingthe power consumption of the apparatus and extending the power of thebattery.

According to the measuring apparatus for an ear thermometer of thepresent invention, the mode switching circuit may employ the CMOSinverter. In an operating state in which the CMOS inverter outputs thecommon voltage, the common voltage is supplied as the HIGH voltage tothe test port of the microcontroller. When the CMOS inverter isinverted, the voltage of the regulator is set as the LOW voltage and issupplied to the test port of the microcontroller. In the run mode of themicrocontroller, which is a normal operating state of the same, nobattery current is passed to the mode switching circuit. As a result,the insertion of the mode switching circuit causes no substantial changein power consumption. This results in suppressing the power consumptionof the apparatus and extending the power of the battery.

According to the measuring apparatus for an ear thermometer of thepresent invention, the probe connector is connected to the connector, sothat the short-circuited two terminals of the probe connector connectthe battery power source terminal and common voltage terminal to eachother. The program write unit connector is connected to the connector,so that the voltage terminal of the second predetermined voltage of theprogram write unit connector is connected to the common voltageterminal. Depending on whether the connector is connected to the probeconnector or the program write unit connector, there will be the normalrun mode established by applying the battery voltage to the commonvoltage line or the program write mode established by applying theprogram write voltage to the common voltage line. Without letting anoperator think of the mode switching, the microcontroller performs themode switching operation.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 A block diagram of an ear thermometer according to an embodimentof the present invention.

FIG. 2 A circuit block diagram of the ear thermometer of the embodiment.

FIG. 3 A partly broken side view of a probe constituting the earthermometer of the embodiment.

FIG. 4 A vertical sectional view of a sensor mirror constituting theprobe in the ear thermometer of the embodiment.

FIG. 5 A plan view of a flexible printed circuit board constituting thesensor mirror in the ear thermometer of the embodiment.

FIG. 6 A front view of the sensor mirror seen from a line VI-VI of FIG.4.

FIG. 7 A perspective view of the sensor mirror seen from the directionof an arrow VII of FIG. 6.

FIG. 8 A perspective view of the sensor mirror seen from the directionof an arrow VIII of FIG. 6.

FIG. 9 A circuit diagram of a resistance value output circuit in the earthermometer of the embodiment.

FIG. 10 A circuit block diagram of a mode switching function part of anMCU in a measuring apparatus for the ear thermometer of the embodiment.

FIG. 11 An explanatory view of connector connection between themeasuring apparatus and the probe for the ear thermometer of theembodiment.

FIG. 12 An explanatory view of connector connection between themeasuring apparatus and a program write unit for the ear thermometer ofthe embodiment.

FIG. 13 A circuit block diagram of a mode switching function partincluding a mode switching circuit in a measuring apparatus according toa second embodiment of the present invention.

FIG. 14 A circuit block diagram of a mode switching function partincluding a mode switching circuit in a measuring apparatus according toa third embodiment of the present invention.

FIG. 15 A block diagram illustrating an operation principle of aconventional ear thermometer.

FIG. 16 A vertical sectional view of a temperature measuring part in theconventional ear thermometer.

BEST MODE OF IMPLEMENTING INVENTION

Embodiments of the present invention will be explained in detail withreference to the drawings.

FIG. 1 illustrates a device configuration of an ear thermometeraccording to an embodiment of the present invention and FIG. 2illustrates a circuit configuration thereof. As illustrated in FIG. 1,the ear thermometer 1 according to this embodiment has a probe 2 that isinserted into an ear hole of an object person, to measure thetemperature of an eardrum and output a resistance value representativeof the measured temperature, a cable 3 to transmit a measurement signalof the probe 2 and supply power to the probe 2, a male connector 4, ameasuring apparatus 5 to perform a temperature measuring process andother control, a cable 6 connected to the measuring apparatus 5, and afemale connector 7 connected to a front end of the cable 6. The femaleconnector 7 connected to the cable 6 of the measuring apparatus 5 isconnected to a monitor 8 to display a measured temperature.

As illustrated in FIG. 2, main components of the measuring apparatus 5include an AD converter 51 to conduct an AD conversion on a resistancevalue corresponding to a measured temperature from the probe 2, adifferential amplifier 52 to amplify a temperature measurement signalfrom the probe 2, a control signal processing circuit 53 to conductdigital computations, a resistance value output circuit 54 to againconvert the measured temperature digital signal provided by the controlsignal processing circuit 53 into a temperature corresponding analogresistance value for the monitor 8, a switch group 55 (switches S1, S2,and S3), a switching line group 56 (SL1, SL2, and SL3), a resistor group57 (R1, R2, R3, and R4), the cable 6, and the female connector 7.

In use, the probe 2 is connected through the cable 3 and male connector4 to a connector 501 (refer to FIGS. 11 and 12) of the measuringapparatus 5. The probe 2 has a temperature measuring first sensor 25 anda correcting second sensor 26 to be explained later. The sensors 25 and26 are made of thermistors. In FIG. 2, the resistors R3 and R4 arearranged in the probe 2. They may be arranged in the measuring apparatus5. The male connector 4 is preferably a usual card edge connector. Thiscard records individual information such as a calibration value.

The temperature measuring first sensor 25 and correcting second sensor26 of the probe 2 send detection signals through the resistors R3 and R4to the AD converter 51 and through the switches S2 and S3 to thedifferential amplifier 52.

The AD converter 51 is connected to the control signal processingcircuit 53 and differential amplifier 52 and the control signalprocessing circuit 53 is connected to the resistance value outputcircuit 54. The control signal processing circuit 53 outputs a digitalsignal and the resistance value output circuit 54 outputs an analogsignal. The control signal processing circuit 53 is connected throughthe switching line group 56 to the switch group 55. The switch group 55is connected to the differential amplifier 52.

To easily detect weak temperature difference signals from the firstsensor 25 and second sensor 26, it is preferable to provide the ADconverter 51 with high precision and high resolution. The resistors R1,R2, R3, and R4 are high precision resistors. Vref is a reference voltagefor the AD converter 51 and is a full scale value of an AD convertedvalue.

As illustrated in FIGS. 3 to 8, the probe 2 according to the embodimentincludes a probe body 21, a temperature measuring part 22 connected tothe probe body 21, and a tab 23 arranged along an outer side of theprobe body 21. The probe body 21 is formed in a cylindrical body bentinto substantially an L-shape having a long part 211 and a short bentpart 212. The long part 211 extends downward from the ear hole 9 a ofthe object person 9 along the temple on the face of the object person.The short bent part 212 engages with a flange 221 to be explained laterof the temperature measuring part 22. This substantial L-shape orients afront end part 222 of the temperature measuring part 22 toward theeardrum in the ear hole 9 a of the object person 9, and when worn,prevents the probe body 21 from dropping off the auricle or from turningaround the auricle. From a lower end of the probe body 21, the cable 3extends to electrically connect a flexible printed circuit board 246 onwhich the first sensor 25 and second sensor 26 to be explained later arearranged to the male connector 4. The tab 23 makes it easy to attach anddetach the probe 2 to and from the ear hole 9 a of the object person 9.

The temperature measuring part 22 includes the flange 221 joined withthe short bent part 212 of the probe body 21 and the front end part 222extending from the flange 221. The flange 221 is formed to close theentrance of the ear hole 9 a and the front end part 222 is formed tomeet a complicated shape of the external auditory.

The probe body 21, temperature measuring part 22, tab 23, and sensormirror 24 that constitute the probe 2 are made from heat insulatingmaterials. The temperature measuring part 22 is preferably covered withelastomer or silicon rubber in consideration of an allergy of the objectperson 9.

As mentioned above, the probe 2 of the ear thermometer 1 according tothe embodiment includes the probe body 21, temperature measuring part22, and tab 23. The temperature measuring part 22 includes the flange221 and front end part 222. As illustrated in FIG. 3, the front end part222 of the temperature measuring part 22 incorporates the sensor mirror24. The sensor mirror 24 is any one of a parallel light condensingsensor mirror illustrated in FIG. 3 and a spot light source condensingsensor mirror illustrated in FIG. 4. The parallel light condensingsensor mirror condenses parallel light in front of a cylindrical holderinto a sensor. The spot light source condensing sensor mirror condenseslight from a spot light source at an assumed eardrum position. Thesensor mirror 24 is a separate part from the temperature measuring part22 so that the sensors 25 and 26 may easily be assembled.

The sensor mirror (spot light source condensing sensor mirror) 24 ismade from an insulating material, and as illustrated in FIG. 4, includesthe cylindrical holder 242 that is relatively long and incorporates aconcave reflection face 241, a joint shaft 245 extending from the backof the holder 242, the flexible printed circuit board 246 to beexplained later stretched in front of the holder 242, the temperaturemeasuring first sensor 25 and correcting second sensor 26 to beexplained later attached to the board 246, and a protection cover 27covering a front face of the holder.

The reflection face 241 of the sensor mirror 24 preferably keeps amirror-finished material surface, or is a metal (for example, aluminum)foil attached to the material surface, or is plated with nickel. Theprotection cover 27 is made of a material that suppresses a radiationenergy loss and protects the sensors 25 and 26. For example, it is madeof a polyethylene film of 0.015 mm in thickness. The protection cover 27is pushed into a gap between an outer circumferential face of thecylindrical holder 242 and joint shaft 245 of the sensor mirror 24 andan inner circumferential face of the opening of the front end part 222of the temperature measuring part 22 and is fixed thereto.

As illustrated in FIG. 5, the flexible printed circuit board 246 is anelongated film made of flexible insulating material (for example,polyethylene) on which a circuit conductor 246 d and a heat sink 246 eare printed. In addition, it has an infrared transmission hole 246 c, afirst positioning hole 246 a, and a second positioning hole 246 b formedtherethrough. Actions of them will be explained later.

As illustrated in FIGS. 4 and 6 to 8, a first projection 242 a andsecond projection 242 b are formed at opposing intermediate positions onthe outer circumferential face of the cylindrical holder 242 of thesensor mirror 24. As illustrated in FIG. 5, the first positioning hole246 a and second positioning hole 246 b are formed on a first end sideof the flexible printed circuit board 246 at positions corresponding tothe first projection 242 a and second projection 242 b. The firstprojection 242 a and second projection 242 b are fitted into the firstpositioning hole 246 a and second positioning hole 246 b, respectively.Consequently, the first end side of the flexible printed circuit board246 is easily stretched in a front space of the cylindrical holder 242of the sensor mirror 24.

A second end side of the flexible printed circuit board 246 is guidedalong the outer circumferential face of the cylindrical holder 242 in alongitudinal direction and is connected to a connection board 213embedded in a front end of the probe body 21. As illustrated in FIG. 3,the second end of the flexible printed circuit board 246 on which thesensors 25 and 26 are arranged is connected through the connection board213 to the front end of the cable 3. In this way, the flexible printedcircuit board 246 is electrically connected, in the temperaturemeasuring part 22, to the cable 3 passing through the inside of theprobe body 21.

As illustrated in FIGS. 4 and 6 to 8, the first end side of the flexibleprinted circuit board 246 is stretched in the front space of thecylindrical holder 242. As illustrated in FIG. 5, the infraredtransmission hole 246 c is formed at an intermediate part of theflexible printed circuit board 246 that corresponds to an assumedlocation in the front space of the cylindrical holder 242 where theboard is stretched. On each side of the infrared transmission hole 246 cin a longitudinal direction of the board 246, the first sensor 25 andsecond sensor 26 are arranged. Before stretching the flexible printedcircuit board 246 in the front space of the cylindrical holder 242, thesensors 25 and 26 are soldered to the circuit conductor 246 d of theboard 246. This allows the sensors 25 and 26 to easily be attached tothe sensor mirror 24, and therefore, the temperature measuring part 22becomes mass-producible without skills. Infrared rays from the objectperson 9 pass through the infrared transmission hole 246 c of the board246, are reflected by the reflection face 241 of the sensor mirror 24,and reach the sensors 25 and 26.

Also, as illustrated in FIG. 5, at an intermediate part of the flexibleprinted circuit board 246 that corresponds to the assumed location inthe front space of the cylindrical holder 242 where the board isstretched, the heat sink conductor 246 e is preferably arranged on thefirst end side of the board 246. The heat sink conductor 246 e absorbsinfrared rays that reach the board 246 and prevents a secondary thermalinfluence from acting on the sensors 25 and 26.

According to a reading test, it has been found that the reading of theprobe 2 is influenced by an ambient temperature. For this, anothersensor (second sensor 26) is arranged in addition to the temperaturemeasuring sensor (first sensor 25), to correct the influence of anambient temperature.

The first sensor 25 and second sensor 26 are preferably thermistorelements that have small thermal capacities, high thermal sensitivities,high infrared reactive temperature increases, and other characteristics.

According to tests, it has been confirmed that a temperaturedistribution having a highest condensing spot appears on the flexibleprinted circuit board 246 stretched in the front space of thecylindrical holder 242 of the sensor mirror 24. Accordingly, asillustrated in FIG. 4, the temperature measuring first sensor 25 isarranged substantially at a condensing point of the reflection face 241of the sensor mirror 24. The ambient temperature correcting secondsensor 26 is arranged at a position out of the condensing point. Sincethe sensors 25 and 26 are on the same board, they substantiallysimultaneously increase their temperatures, and therefore, a correctionis easy. The first sensor 25 is coated with resin (for example,black-color thermosetting epoxy resin) that has a high emissivity (wellabsorbing infrared rays and generating heat) and easily radiates heatgenerated by infrared rays. The second sensor 26 is coated with resin(for example, two-component setting epoxy resin) that hardly absorbsinfrared rays.

The first sensor 25 and second sensor 26 are simultaneously calibratedfor temperatures. For the temperature calibration, the measuringapparatus 5 illustrated in FIG. 2 is used to measure a body temperatureof the object person 9. First, the probe connector 4 is connected to themeasuring apparatus 5 and the temperature plug 7 is connected to themonitor 8.

a) Offset Calibration

In the switch group 55, the switch S1 is set to ON and the switches S2and S3 to OFF. An AD conversion is carried out to find an offset value.Since the resistors R1 and R2 are known, an AD input value is known. Adifference between the AD converted value and the AD input value is anoffset error of the differential amplifier 52 and AD converter 51. An ADconverter input V1 at the time of offset calibration is expressed asR2/(R1+R2)×Vref. In the case of a high precision AD converter, aself-calibration is carried out at each measurement, and therefore, theoffset error of the AD converter is ignorable. Accordingly, the offseterror is substantially from the differential amplifier 52.

b) Measurement of First Sensor 25

The switch S2 is set to ON and the switches S1 and S3 to OFF. An ADconversion is carried out to find an AD converted value. An ADconversion input V2 at the time of measurement of the first sensor 25 isexpressed as R3/(R3+RTh1)×Vref, where RTh1 is a resistance value of thefirst sensor 25 at an arbitrary temperature.

c) Measurement of Second Sensor 26

The switch S3 is set to ON and the switches S1 and S2 to OFF. An ADconversion is carried out to find an AD converted value. An ADconversion input V3 at the time of measurement of the second sensor 26is expressed as R4/(R4+RTh2)×Vref, where RTh2 is a resistance value ofthe second sensor 26 at an arbitrary temperature.

d) Difference Between Ad Converted Values of First Sensor 25 and SecondSensor 26

From the AD converted value of the first sensor 25, the offset valuefound by the offset calibration is subtracted. From a relationship ofthis value and a difference between the AD converted values of the firstsensor 25 and second sensor 26, the temperature of a measurement targetpoint is found.

The measured temperature data is provided as a digital signal from thecontrol signal processing circuit 53 that is an MCU (microcontroller).The resistance value output circuit 54 outputs an analog signal. Theanalog signal enables the temperature detected by the sensors(thermistors) to be displayed on the monitor 8.

An analog signal representative of a measured temperature correspondingresistance value is converted by the control signal processing circuit53 into a digital signal, which is supplied to the resistance valueoutput circuit 54. The resistance value output circuit 54 is an 11-bitanalog-digital conversion circuit having a configuration illustrated inFIG. 9 and converts the digital signal representative of a temperaturevalue into an analog resistance value. Namely, ports P0 to P10 of thecontrol signal processing circuit 53 output a digital signal of elevendigits of ONs and OFFs. In response to the digits, analog switches AN0to AN10 of digit bits open (OFF) if 1 (HIGH) and close (ON) if 0 (LOW).As a result, a serial composition resistance value of resistors Ri ofthe bits whose analog switches ANI are opened is converted into aresistance value Rout that corresponds to the digital signalrepresentative of the temperature value. Between terminals A and B ofthe resistance value output circuit 54, a bias voltage of one half ofVcc, i.e., 1.5 Vcc is applied. Accordingly, between the terminals A andB, a current Iout (=Vcc/2Rout) corresponding to the resistance valueRout is outputted. The monitor 8 considers the current Iout as a currentpassing through the thermistor, finds a resistance value correspondingto the current, converts the resistance value into a temperature, anddisplays the temperature.

The measuring apparatus 5 is intended to continuously measure thetemperature of the object person for a long period of time according toa sequence of operations of (a) calibration, (2) measurement of thefirst sensor 25, (3) measurement of the second sensor 26, (4)calculation of a measured temperature, and (5) output of temperaturedata. The operations (1) to (5) are continuously repeated.

With this, according to the ear thermometer of the embodiment, thesensors (thermistors) used for the probe must keep an accuracy only fora temperature range in which the temperature of an object person varies.Unlike the conventional ear thermometer employing a thermopile, it isnot necessary for securing a thermistor measurement accuracy for anentire range of ambient temperatures. Under a relatively stable ambienttemperature, the embodiment can continuously measure temperatures for along period of time. The sensors are soldered to the circuit conductorof the flexible printed circuit board in advance, to simplify assemblingwork. This is advantageous for mass production. In addition, thetemperature measuring circuit is simple, the temperature calibration issimple, and the probe is miniaturized, to reduce the size and cost ofthe ear thermometer.

Next, with reference to FIGS. 10 to 12, a mode switching circuit 500 forthe microcontroller MCU serving as the control signal processing circuit53 incorporated in the measuring apparatus 5 will be explained.

As illustrated in FIG. 10, the microcontroller MCU has many input/outputports. Here, only ports related to program writing (including newwriting and overwriting) to a built-in flash memory FLM are illustrated.The MCU includes a test port 531, a common voltage input port 532, averify signal port 533, a program write port 534, and a temperaturesignal input port 535 and incorporates a central processing unit CPU andthe flash memory FLM.

For this MCU, the mode switching circuit 500 is externally arranged. Themode switching circuit 500 receives a common voltage Vcc from the commonvoltage line and has a transistor QR that becomes conductive if thecommon voltage Vcc is higher than a predetermined voltage of 4 V andnonconductive if it is lower than that. The mode switching circuit 500also has base bias resistors R5 to R7. A collector end of the transistorQR is connected to the test port 531 of the MCU and is also connectedthrough a resistor R8 to the ground GND.

The bias resistor R5 of the mode switching circuit 500 receives thecommon voltage Vcc and is connected to an output line of a regulator 58that provides the AD converter 51 with the predetermined voltage Vref. Acurrent passing through the bias resistor R5 is joined with an outputcurrent of the regulator 58. As explained with reference to FIG. 2, theAD converter 51 converts a resistance value analog signal correspondingto a temperature detected signal of the temperature measuring probe 2into a digital signal and supplies the digital signal to the temperaturesignal port 535 of the microcontroller MCU.

The reference voltage Vref for the AD converter 51 is 2.2 V. Theregulator 58 applies the voltage Vref of 2.2 V to the AD converter 51.The common voltage line Vcc is 5 V. The resistors are R8=30 KΩ,R6=R7=100 KΩ, and R5=90 to 95 KΩ. With these values, the transistor QRturns on (conductive) if Vcc is higher than 4 V and turns off(nonconductive) if Vcc is lower than 4 V. Namely, if the voltage Vcc ofthe common voltage line is 5 V, the test port 531 of the microcontrollerMCU receives a HIGH voltage, to shift the MCU to a program write mode.On the other hand, if the voltage Vcc of the common voltage line is 3 V,the test port 531 of the microcontroller MCU receives a LOW voltage toput the MCU in a normal run mode.

As illustrated in FIGS. 11 and 12, the connector 501 of the measuringapparatus 5 is provided with terminals GND, TH1, and TH2 connected tothe ground terminal GND and thermistor signal terminals TH1 and TH2 ofthe male connector 4 of the temperature measuring probe 2, respectively,a battery power source terminal BT connected to the built-in battery502, a common voltage terminal VC connected to the internal commonvoltage line Vcc and a common voltage terminal VC of a write unitconnector 4′ of the program write unit, a program write terminal PG toreceive write data from the write unit connector 4′, and a verify signalterminal VF to output a verify signal.

As illustrated in FIG. 11, on the male connector 4 of the temperaturemeasuring probe 2, terminals VA and VB connected to the battery powersource terminal BT and common voltage terminal VC of the apparatusconnector 501 are short-circuited. As a result, when the male connector4 is inserted into and connected to the apparatus connector 501, thebattery power source terminal BT and common voltage terminal VC areconnected to each other through the terminals VA and VB of the maleconnector 4, to apply a battery voltage (normally, about 3 V) to thecommon voltage line Vcc in the measuring apparatus 5, thereby activatingthe measuring apparatus 5 to use the ear thermometer 1.

On the other hand, as illustrated in FIG. 12, the program write unit isprepared to write an initial program into the microcontroller MCU, or afirmware upgrade program into the flash memory FLM. When the write unitconnector 4′ is inserted into and connected to the apparatus connector501, the common voltage terminal VC of a high common voltage Vcc of 5 V,program write terminal PG, verify signal terminal VF, and groundterminal G of the unit are connected to the common voltage terminal VC,program write terminal PG, verify signal terminal VF, and groundterminal G of the apparatus connector 501, respectively. As a result,the high voltage of 5 V necessary for writing a program to the MCU isapplied from the program write unit to the common voltage line Vccthrough the common voltage terminals VC.

Next, the mode switching circuit 500 and a mode switching operation ofthe microcontroller MCU will be explained.

[Program Write Mode]

If a requirement arises to write a program for operating the earthermometer of the embodiment into the flash memory FLM in the MCU, orupdate the program, the program write unit illustrated in FIG. 12 isprepared and the connector 4′ of the write unit is connected to theapparatus connector 501. As a result, the common voltage terminal VC of5 V, program write terminal PG, verify signal terminal VF, and grandterminal G of the program write unit connector 4′ are connected to thecommon voltage terminal VC, program write terminal PG, verify signalterminal VF, and grand terminal G of the apparatus connector 501,respectively. Then, the common voltage terminals VCs pass the highvoltage of 5 V necessary for writing a program to the MCU from theprogram write unit to the common voltage line Vcc. With this, the MCUshifts to the program write mode, i.e., a flash mode as mentioned below.

The connection of the program write unit sets the voltage Vcc of thecommon voltage line to the high voltage of 5V. This puts the transistorQR in a conductive state and the voltage of the test port 531 becomesHIGH. Accordingly, the MCU shifts to the flash mode and the CPU writesdata from the program write port 534 into the flash memory FLM andoutputs a verify signal from the verify signal port 533 to the programwrite unit.

[Run Mode]

On completion of the program writing or updating, the program write unitis removed and the male connector 4 of the temperature measuring probe 2is connected to the apparatus connector 501 as illustrated in FIG. 11.Then, the microcontroller MCU shifts to the run mode to start atemperature measuring operation as mentioned below.

When the male connector 4 of the temperature measuring probe 2 isconnected to the apparatus connector 501, the terminals VA and VB of themale connector 4 connect the battery power source terminal BT and commonvoltage terminal VC of the apparatus connector 501 of the apparatus 5 toeach other, to apply the battery voltage (normally, about 3 V) to thecommon voltage line Vcc in the measuring apparatus 5. The mode switchingcircuit 500 puts the transistor QR in a nonconductive state as mentionedbelow, to bring the voltage applied to the test port 531 of themicrocontroller MCU to LOW, switch the MCU to the normal operatingstate, i.e., the run mode, activate the measuring apparatus 5, andenable the ear thermometer 1.

When the battery 502 applies the common voltage Vcc=3 V, a voltagedifference between the common voltage Vcc and the output voltage of theregulator 58, i.e., the reference voltage Vref=2.2 V is 0.8 V. Anemitter-base open voltage of the transistor QR is −0.28 V and an ONvoltage of the base of the transistor QR is −0.6 V. Accordingly, thetransistor QR turns off and the voltage of the test port 531 becomes LOW0V. Then, the MCU determines that it is the run mode and shifts to therun mode to execute the program written in the flash memory FLM.

In this run mode, a current passed to the resistor R8 is about 6 μA,which is a very small current. The current passed to the resistor R8 iscombined with a current from the regulator 58 and the combined currentis supplied to the AD converter 51. Accordingly, a current supplied fromthe common voltage line Vcc to the regulator 58 is decreased by aportion that is equal to the current passed to the resistor R8. Namely,according to the mode switching circuit 500 of the embodiment, a currentconsumed by adding the circuit in question is substantially zero.

As mentioned above, the addition of the mode switching circuit 500 ofthe embodiment needs no mode switch that is usually needed to switch amode of the MCU to another, simplifies a circuit configuration,suppresses a cost increase and a circuit area increase, and promotes theminiaturization of the measuring apparatus 5. In addition, the additionof the mode switching circuit 500 substantially involves no increase incurrent consumption, and therefore, reduces the consumption of thebuilt-in battery 502.

The resistance values and transistor's characteristic values related tothe embodiment are only examples, are not intended to restrict thepresent invention, and are modifiable depending on the use, size, scale,and other specifications of the apparatus.

The mode switching circuit 500 may be the one employing an operationalamplifier OP2 illustrated in FIG. 13 (second embodiment) or the oneemploying a CMOS inverter U1 illustrated in FIG. 14 (third embodiment).

The mode switching circuit 500A illustrated in FIG. 13 will beexplained. Between the common voltage line Vcc and the ground GND,resistors R6A and R7A are connected in series. A connection midpoint ofthe resistors R6A and R7A is connected to a plus input terminal of anoperational amplifier OP2 operating as a comparator. A minus terminal ofthe operational amplifier OP2 is connected through a resistor R5A to theoutput line of the regulator 58. An output of the operational amplifierOP2 is connected to the test port 531 of the microcontroller MCU, sothat the test port 531 may receive HIGH and LOW voltages that areswitched from one to another. According to the mode switching circuit500A, the regulator 58 outputs Vref=2.2 V and the operational amplifierOP2 switches at 4 V that is between the high voltage of 5 V from theprogram write unit and the low voltage of 3 V (normal voltage) from thebuilt-in battery 502. When the program write unit is connected to setthe common voltage Vcc=5 V, the operational amplifier OP2 inverts sothat the common voltage Vcc is stepped down through the resistor R6A toVth, which is supplied as the HIGH voltage to the test port 531 of theMCU, thereby shifting the MCU to the program write mode. On thecontrary, when the connector 4 of the temperature measuring probe 2 isconnected, the common voltage Vcc is set to the voltage of 3 V of thebattery 502, to again invert the operational amplifier OP2. Then, theoutput Vref of the regulator 58 is stepped down through the resistor R5Aand is supplied as the LOW voltage to the test port 531 of the MCU,thereby shifting the MCU to the normal operation mode, i.e., the runmode. The mode switching operation of the MCU is the same as that of thefirst embodiment mentioned above.

According to this embodiment, the resistors R6A and R7A are connected tothe plus side of the operational amplifier OP2, and therefore, a veryhigh impedance input is allowed. Due to this, the resistors R6A and R7Amay be high resistance value elements. Then, like the first embodiment,substantially no current passes from the common voltage line to theground when the operational amplifier OP2 performs no invertingoperation. This suppresses consumption of the battery.

The mode switching circuit 500B illustrated in FIG. 14 will beexplained. Between the common voltage line Vcc and the ground GND, aCMOS inverter U1 is arranged. A switching terminal thereof and theoutput of the regulator 58 are connected to each other through aresistor R5B. The switching terminal and the ground are connected toeach other through a resistor R6B. The CMOS inverter U1 inverts anoutput in response to an input that is a half of a current detectionvoltage. Accordingly, the resistors R5B and R6B are so set that theswitching terminal may receive a voltage of 2 V that is stepped downfrom the reference voltage Vref=2.2 V from the regulator 58. Then, whenthe common voltage Vcc exceeds 4 V, the common voltage Vcc is suppliedas HIGH to the test port 531 of the microcontroller MCU, and when thecommon voltage Vcc drops below 4 V, it is inverted to the LOW voltagewhich is supplied to the test port 531 of the MCU.

When the program write unit is connected to set the common voltage Vcc=5V, the CMOS inverter U1 of the mode switching circuit 500B inverts tosupply the common voltage Vcc as the HIGH voltage to the test port 531of the MCU, thereby shifting the MCU to the program write mode. When theconnector 4 of the temperature measuring probe 2 is connected to set thecommon voltage Vcc to the voltage of 3 V of the battery 502, the CMOSinverter U1 again inverts to supply the LOW voltage=0 to the test port531 of the MCU, thereby shifting the MCU to the normal operation mode,i.e., the run mode. The mode switching operation of the MCU is the sameas that of the first embodiment.

This embodiment can also adopt a high resistance element as the resistorR6B. Like the first embodiment, substantially no current passes from thecommon voltage line to the ground when the CMOS inverter U1 is in astate not to invert. This suppresses consumption of the battery.

INDUSTRIAL APPLICABILITY

The ear thermometer of the present invention is applicable not only tohumans but also to animals.

1-4. (canceled)
 5. A measuring apparatus for an ear thermometercomprising: a common voltage line; a built-in battery serving as a powersource; a connector to receive a connector of a probe, having a commonvoltage terminal connected to the common voltage line; a flash-typemicrocontroller to control a temperature sensor of the probe, receive aresistance value output signal corresponding to a measured temperaturefrom the temperature sensor, convert the signal into a digitaltemperature value, and output the digital temperature value, themicrocontroller having a test port, a program write port, and a commonvoltage port connected to the common voltage line, establishing a flashmode when a HIGH voltage higher than a first predetermined voltage isapplied to the test port, to enable a program to be written through thewrite port, and establishing a run mode when a LOW voltage lower thanthe first predetermined voltage is applied to the test port; a voltageregulator having an input side connected to the common voltage line, toprovide a constant reference voltage; and a mode switching circuitconnected to the common voltage line, to apply the HIGH voltage to thetest port of the microcontroller when a common voltage is higher than asecond predetermined voltage, apply the LOW voltage to the test port ofthe microcontroller when the common voltage is lower than the secondpredetermined voltage, and bypass a leakage current passing from thecommon voltage line to the mode switching circuit toward an output ofthe voltage regulator so as to combine them together, the connectorhaving the common voltage terminal, a battery power source terminalconnected to the built-in battery, a program write terminal connected tothe write port of the microcontroller, and a sensor connection terminalto receive the resistance value output signal corresponding to ameasured temperature from the temperature sensor of the probe.
 6. Themeasuring apparatus for an ear thermometer as set forth in claim 5,characterized in that the mode switching circuit consists of a pnp-typetransistor having an emitter connected to the common voltage line, acollector connected to the test port, and a base connected through abias resistor to the common voltage line, a first resistor interposedbetween the collector and the ground, to set a voltage of the collectoras the HIGH voltage when the transistor is in a conductive state, and asecond resistor interposed between the base of the transistor and theoutput of the regulator.
 7. The measuring apparatus for an earthermometer as set forth in claim 5, characterized in that: the modeswitching circuit is constituted by connecting two resistors in seriesbetween the common voltage line and the ground, connecting a plus inputterminal of an operational amplifier operating as a comparator to aconnection midpoint of the two resistors, connecting a minus terminal ofthe operational amplifier through another resistor to the output line ofthe regulator, and connecting an output terminal of the operationalamplifier to the test port of the microcontroller; and when a voltageapplied to the plus terminal of the operational amplifier is higher thanan intermediate voltage between a battery voltage applied to the commonvoltage line and a program write voltage, the operational amplifier isput in a conductive state to output the common voltage of the commonvoltage line as the HIGH voltage to the test port, and when it is lowerthan the intermediate voltage, the operational amplifier is invertedinto a nonconductive state.
 8. The measuring apparatus for an earthermometer as set forth in claim 5, characterized in that: the modeswitching circuit is constituted by arranging a CMOS inverter betweenthe common voltage line and the ground, connecting a switching terminalof the CMOS inverter and the output of the regulator to each otherthrough a resistor, and connecting an output of the CMOS inverter to thetest port; and when a voltage applied to the switching terminal of theCMOS inverter is higher than an intermediate voltage between a batteryvoltage applied to the common voltage line and a program write voltage,the common voltage of the common voltage line is outputted as the HIGHvoltage to the test port, and when it is lower than the intermediatevoltage, an output voltage from the regulator stepped down through theresistor is outputted as the LOW voltage to the test port.
 9. Themeasuring apparatus for an ear thermometer as set forth in claim 5,characterized in that the connector is configured so that, whenconnected to the probe connector, the battery power source terminal andcommon voltage terminal are connected to each other throughshort-circuited two terminals of the probe connector, and when connectedto a program write unit connector, the common voltage terminal isconnected to a voltage terminal of the second predetermined voltage ofthe program write unit connector.